The goal of the proposed research is to evaluate and develop techniques for the application of the triple quadrupole mass spectrometer in the determination of molecular structure. In triple quadrupole mass spectrometry (TQMS), ions from the source are selected by mass in the first quadrupole and then undergo fragmenting or reactive collision(s) with neutral molecules in the non mass-selective center quadrupole. The ionic collision products are then mass-analysed by the third quadrupole before detection. This is a form mass spectrometry (MS/MS). With TQMS or MS/MS, one can obtain a spectrum for every "parent" ion produced in the source. This three-dimensional collection of spectra contains much more information about the sample than the oridinary mass spectrum. It is a goal of this proposal to deduce the structural information contained in these spectra by comparison of the daughter spectra with those from a large number of compounds with known and varied structure. The proposed research includes four areas: 1) a continuation of our effort to identify the structural information contained in the variations in daughter spectra with changes in ion internal energy, ion kinetic energy, and collision gas pressure and to identify reasonable and reproducible "standard" conditions for the collection of spectra for a data base library, 2) the development of searching and ranking procedures which will produce lists of compounds in the data base that produce ions that give daughter spectra similar to those of the unknown compound. 3) The development of algorithms to identify from the lists of compounds, those common substructures which might be part of the unknown compound and from them produce a list of possible structures, and 4) make certain improvements in the instrumentation and data base management software to facilitate the above goals. Efficient organic structural analysis is a major need among synthetic, environmental and pharaceutical chemists as well as toxicologists and pathologists.